1. Technical Field
The present invention relates to a portable system to purge and dry the environment within a sealed Vessel.
2. Related Background Art
Vessels that operate in harsh environments such as space, under the sea and in extreme heat or cold environments frequently are sealed against these environments to protect equipment and content of the vessel. In many cases where a vehicle operates in cold environment it is important to control the internal moisture of the vessel to avoid condensation and/or freezing on the vessel walls and on equipment surfaces within the vessel. One example of such vessels includes free vessels used to carry equipment to the ocean floor and back. In one example these vessels are made of glass spheres to allow photograph and other observations to be made through the walls of the vessel. It is therefore important that the walls of the vessel and the photographic equipment are kept free of condensation. Frequently the equipment is setup and deployed while the user is in or around the harsh environments. They are frequently in cramped quarters and do not have access to the equipment typically used for purge and desiccation of vessels that is available on land in a laboratory or factory.
Dry nitrogen gas is frequently used to prepare a vessel for deployment by sweeping the interior with a flow of dry nitrogen from a cylinder. In the marine or space environment however the supply of dry nitrogen is limited or non-existent. Compressed nitrogen tanks that have sufficient capacity to purge a vessel are typically too large to fit in cramped quarters where a vessel is to be deployed in the field. Lack of sufficient supply can render experiments useless. Cylinders are almost always re-filled at a land-based station. Once the supply of nitrogen in a cylinder is exhausted no more purging can be accomplished.
Frequently the goal of a purge process is to remove moisture from the air within a vessel to a pre-selected humidity level. The pre-selected level may be on the basis of the dew point at the operating temperature of the vessel or on the basis of other factors. Some vessels may require an air environment with a controlled amount of humidity. Such an environment cannot be accomplished using dry compressed nitrogen. It some cases dry compressed air is used for purging but this again has the limits of a supply tank capacity. In some cases the equipment within the vessel cannot withstand reduced or elevated air pressure or at least has an operating range for air pressure. There is a need for a purge system that controls the air pressure within the vessel during the purge process.
In other cases the purge is done to a setting to detect other chemicals within the vessel environment. There are currently known general-purpose purge devices that can take a variety of input sensors and programmatically purge a connected vessel to attain a pre-selected constituent level. In some cases the chemical constituent is the oxygen level within the vessel, in others in is the level of a harmful or flammable constituent.
There is a need for a compact, portable, lightweight, controllable and renewable portable purge system. There is a need for a system that can automatically purge a vessel to a controlled humidity level while maintaining the air pressure within the vessel to a pre-selected range. There is a need for a system that is compact and renewable. There is a need for a system that does not require bulky and heavy compressed gas tanks.